The invention relates to the controlled extraction of compressed air from a cylinder of Diesel engine by way of a decompression valve which is operated by fuel available from a high pressure fuel line, wherein the admission of high pressure fuel to the decompression valve is controlled by an electromagnetic control valve.
In principle, such apparatus are known from the German patent specifications DE 39 04 497 C1 and DE 43 09 860 C1.
With the apparatus disclosed in these references, the air compressed in a cylinder by a piston of a Diesel engine can be supplied selectively to a compressed air line leading to a compressed air storage tank or to the exhaust system of the engine. the air is extracted from the cylinder by way of a control valve disposed in the cylinder head. The control valve is opened when the pressure of the air compressed in the cylinder has reached for example a predetermined operating pressure of the compressed air tank.
For actuating the control valve, a pressurized hydraulic or pneumatic control fluid is admitted to a control cylinder which is connected to the control valve.
The control valve may be for example, the decompression valve which is anyhow present in most Diesel engines.
The high pressure fluid may be provided by high pressure pumps. Such pumps by which high fluid pressures for common oil fluid supply systems can be generated, are well known in the art.
The expression "common rail" refers to high pressure conduits in which a sufficiently high fluid pressure is maintained to provide high pressure fluid to various consumers such as hydraulic or pneumatic operating cylinders.
It is the object of the present invention to provide an arrangement by which compressed air can be extracted from cylinders of a Diesel engine for supply to a compressed air tank or for other uses or purposes in a simple and accurately controllable manner utilizing high pressure fluid provided by a high pressure fluid pump present in a Diesel engine.